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1c) Forces, movement & shape (types of force (Gravitational (this is…

A force is balanced when two equal forces push or pull in the opposite direction, like a draw in a Tug of War.

An unbalanced force is when one force is larger than the other. The object will then change its speed or the direction it is moving in.

Force

a force is a push of pull

force can cause n object to:

Speed up

Slow down

change direction

change shape

force is measured in newtons (N)

and measured with a newtonmeter

types of force

Gravitational

this is the attractive force exerted between bodies because of their masses

Weight is the gravitational force of the Earth on an object

friction

this force opposes motion

the kenetic energy of the moving object is converted to heat energy by the force of friction

Air resistance or drag

this is the force that opposes the movement of objects through air

Drag is a more general term used for the opposite force in any liquid or gas.

Upthrust

this is the force experienced by objects when they are placed into a fluid

An object will float on a liquid if the upthrust force equals its weight

magnetic

between magnets but also the force that allows electric motors to work

Electrostatic

attractive and repulsive forces due to bodies being charged

Friction - a force that opposes motion.

the relationship between gravity, mass and wieght

terminal velocity

When first an object is falling it is accelerating- the force acting downward (gravity) is larger than the force acting upwards (air resistance.) But when air resistance and gravity become equal the object will have reached its maximum speed; its terminal velocity.

experiments to investigate

Dropping parachutes from a given height; this shows us that gravity is acting on them. By increasing the size of the parachute and recording the results we can see that air resistance also has an effect on falling objects; plotting a graph should reveal that bigger surface area takes more time, from which we can infer that air resistance acts on the falling objects.

e.g.

Get five different sizes of sycamore seeds

. Roughly measure, and label them with, their surface area by multiplying the length by width

. Hold one at the top of a meter ruler

. Drop it and time how long it takes to reach the ground

. Repeat this three times for each of the five seeds

. Then plot a scatter graph with surface area on the y axis (mm/cm) and time on the x axis (s)

. You should find that the line of best fit is a diagonal line pointing away from 0, this represents a positive correlation meaning the larger the surface area the longer it took to fall

. This is because the larger seeds had more surface area to experience air resistance, this is a type of friction that opposes gravity, therefore slowing down the time taken for gravity to bring them to the ground.

stopping distance

Thinking distance

speed - reaction time

dopiness - tiredness, drugs, old age

Breaking distance

speed - faster you are going the longer it takes to stop

Mass of Vehicle - the larger the mass of a vehicle the longer it takes to stop